Inside air/outside air switching device

ABSTRACT

An inside air/outside air switching device that includes: an inside air/outside air switching case that has an outside air inlet which opens into an engine room, a first inside air inlet and a second inside air inlet which open into a vehicle compartment; an inside air/outside air switching door that is provided in the inside air/outside air switching case, and that switches an open inlet between the first inside air inlet and the outside air inlet; an inside air introduction support door that opens and closes the second inside air inlet; and a noise insulation member that is provided in such a manner that an operation of the inside air introduction support door is not interfered with, and that blocks out noise which is generated in the engine room and which proceeds from the outside air inlet toward the second inside air inlet when the outside air inlet is open.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2008-180517 filed onJul. 10, 2008 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to an inside air/outside air switchingdevice that has a first inside air inlet and a second inside air inletwhich open into a vehicle compartment, and an outside air inlet whichopens into an engine room, and more specifically to a technology forminimizing noise that leaks from the engine room into the vehiclecompartment through the second inside air inlet.

2. Description of the Related Art

An inside air/outside air switching device of the above-mentioned typeis described in, for example, Japanese Patent Application PublicationNo. 2002-137621 (JP-A-2002-137621). In the inside air/outside airswitching device, a second inside air inlet is formed at a positionbetween an inside air/outside air switching door, which switches an openinlet between a first inside air inlet and an outside air inlet, and anair filter, and an inside air introduction support door that opens andcloses the second inside air inlet is provided.

The inside air introduction support door opens the second inside airinlet when the inside air/outside air switching device is in the outsideair introduction mode in which the outside air is drawn into the insideair/outside air switching device through the outside air inlet. Thus,the outside air is introduced into the inside air/outside air switchingdevice through the outside air inlet and part of the inside air isintroduced into the inside air/outside air switching device through thesecond inside air inlet.

When the inside air/outside air switching device according toJP-A-2002-137621 is in the outside air introduction mode in which theoutside air inlet is open, the second inside air inlet is also open.Therefore, engine noise may enter the inside air/outside air switchingdevice through the outside air inlet and then leak into a vehiclecompartment through the second inside air inlet.

SUMMARY OF THE INVENTION

The invention provides an inside air/outside air switching device thathas a first inside air inlet, a second inside air inlet, and an outsideair inlet, and that is structured in such a manner that noise that leaksinto a vehicle compartment through the second inside air inlet isminimized.

An aspect of the invention relates to an inside air/outside airswitching device that includes: an inside air/outside air switching casethat has an outside air inlet which opens into an engine room, a firstinside air inlet which opens into a vehicle compartment, and a secondinside air inlet which opens into the vehicle compartment and which isformed in the side wall of the inside air/outside air switching case; aninside air/outside air switching door that is provided in the insideair/outside air switching case, and that switches an open inlet betweenthe first inside air inlet and the outside air inlet; an inside airintroduction support door that opens and closes the second inside airinlet; and a noise insulation member that is provided in such a mannerthat the noise insulation member does not interfere with the operationof the inside air introduction support door, and that blocks out noisewhich is generated in the engine room and which proceeds from theoutside air inlet toward the second inside air inlet when the outsideair inlet is open. The inside air/outside air switching device accordingthe aspect of the invention may further include an air blasting unitthat is provided at a position which is downstream of the inside airintroduction support door in the direction of air flow, and that takesin the air introduced into the inside air/outside air switching casethrough the inlets. In the inside air/outside air switching device, theinside air introduction support door may be provided at a position thatis downstream of the inside air/outside air switching door in thedirection of air flow and that is on the inner side of the second insideair inlet, may move inward from the inner wall face of the insideair/outside air switching case when the inside air introduction supportdoor opens the second inside air inlet, and may open and close thesecond inside air inlet based on a change in the pressure in the insideair/outside air switching case when the outside air inlet is open, andthe noise insulation member may be provided at a position outside butnear the operation range of the inside air introduction support door.

According to the aspect of the invention described above, the noise thatis generated in the engine room and enters the inside air/outside airswitching case is blocked out by the noise insulation member. With thisstructure, even if the second inside air inlet is open, the noise thatleaks into the vehicle compartment is minimized.

The inside air/outside air switching device described above may furtherinclude an air filter that is provided between the inside airintroduction support door and the air blasting unit, and that filtersthe air introduced into the inside air/outside air switching casethrough the inlets. The noise insulation member may be formed of twoside portions, may have a substantially L-shaped cross section, and maybe provided in such a manner that the noise insulation member covers theinside air introduction support door. The inside face of an end of oneof the side portions may contact the upper end of the inside airintroduction support door. A small space may be left between the lowerend of the other side portion and the air filter. In addition, a smallspace may be left between each of both longitudinal ends of the sideportions and the inner wall face of the inside air/outside air switchingcase.

The noise that is generated in the engine room and enters the insideair/outside air switching case through the outside air inlet proceedstoward the second inside air inlet through the spaces. However, alabyrinth structure is formed because the spaces are small. Therefore,the noise that leaks into the vehicle compartment through the secondinside air inlet is minimized.

The inside air/outside air switching device described above may furtherinclude an air volume adjustment plate that is provided between theinside air introduction support door and the air blasting unit, and thathas a blast resistance which is substantially equal to a blastresistance of an air filter that filters the air introduced into theinside air/outside air switching case through the inlets. The noiseinsulation member may be formed of two side portions, may have asubstantially L-shaped cross section, and may be provided in such amanner that the noise insulation member covers the inside airintroduction support door. The inside face of an end of one of the sideportions may contact the upper end of the inside air introductionsupport door. A small space may be left between the lower end of theother side portion and the air volume adjustment plate. In addition, asmall space may be left between each of both longitudinal ends of theside portions and the inner wall face of the inside air/outside airswitching case.

The noise that is generated in the engine room and enters the insideair/outside air switching case through the outside air inlet proceedstoward the second inside air inlet through the spaces. However, alabyrinth structure is formed because the spaces are small. Therefore,the noise that leaks into the vehicle compartment through the secondinside air inlet is minimized.

The noise insulation member may be formed of two side portions, may havea substantially L-shaped cross section, and may be provided in such amanner that the noise insulation member covers the inside airintroduction support door. The inside face of an end of one of the sideportions may contact the upper end of the inside air introductionsupport door. A space, through which the air that is introduced into theinside air/outside air switching case through the second inside airinlet flows, may be left between the lower end of the other side portionand the upper plate of the air blasting unit.

With this structure, the noise that is generated in the engine room andenters the inside air/outside air switching device through the outsideair inlet is blocked out by the noise insulation member that has thesubstantially L-shaped cross section. Therefore, the noise that leaksinto the vehicle compartment through the second inside air inlet isminimized.

Side plates may be provided at respective longitudinal ends of the noiseinsulation member, and each of the side plates may connect one of theside portions to the other side portion. With this structure, the noisethat leaks into the vehicle compartment is minimized more reliablybecause the length of the spaces in the depth direction is increased.

The pressure in the inside air/outside air switching case when theoutside air inlet is open may be determined based on the pressure of theoutside air that is introduced into the inside air/outside air switchingcase through the outside air inlet and the intake negative pressure thatis generated when the air blasting unit is driven. When the pressure inthe inside air/outside air switching case is lower than the pressure ofthe inside air, the inside air introduction support door may be drawninward from the inner wall face to open the second inside air inlet.When the pressure in the inside air/outside air switching case is higherthan the pressure of the inside air, the inside air introduction supportdoor may be pushed against the inner wall face of the inside air/outsideair switching case to close the second inside air inlet. With thisstructure, a device that generates power for operating the inside airintroduction support door need not be provided, and part of the insideair is introduced into the inside air/outside air switching case throughthe second inside air inlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages, and technical and industrial significance ofthis invention will be described in the following detailed descriptionof example embodiments of the invention with reference to theaccompanying drawings, in which the same or corresponding portions willbe denoted by the same reference numerals, and wherein:

FIG. 1 is a view schematically showing the overall structure of aninside air/out side air switching device according to a first embodimentof the invention;

FIG. 2 is a perspective view showing the appearance of a noiseinsulation member according to the first embodiment of the invention;

FIG. 3 is a partially-cutout perspective view showing the insideair/outside air switching device according to the first embodiment ofthe invention;

FIG. 4 is a front view showing the state in which an inside airintroduction support door is fitted;

FIG. 5 is a graph showing comparison between the noise level when thenoise insulation member according to the first embodiment of theinvention is provided and the noise level when no noise insulationmember is provided;

FIG. 6 is a perspective view showing the appearance of a noiseinsulation member according to a second embodiment of the invention;

FIG. 7 is a view schematically showing the overall structure of aninside air/outside air switching device according to a third embodimentof the invention; and

FIG. 8. is a view schematically showing the overall structure of aninside air/outside air switching device according to a fourth embodimentof the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereafter, an inside air/outside air switching device according to afirst embodiment of the invention will be described with reference toFIGS. 1 to 5. FIG. 1 is a view schematically showing the overallstructure of the inside air/outside air switching device. FIG. 2 is aperspective view showing the appearance of a noise insulation member.FIG. 3 is a partially-cutout perspective view showing the insideair/outside air switching device. FIG. 4 is a front view showing thestate in which an inside air introduction support door is fitted.

As shown FIGS. 1 to 3, the inside air/outside air switching deviceaccording to the first embodiment of the invention includes an insideair/outside air switching case 10 and an air blasting unit 20. Theinside air/outside air switching device is provided at the front portionof a vehicle compartment of a vehicle. The inside air/outside airswitching device is arranged below a dashboard and on the side of afront passenger seat. The inside air/outside air switching case 10 isformed of a case made of synthetic resin, and the air blasting unit 20is connected to the bottom of the inside air/outside air switching case10. The inner space of the inside air/outside air switching case 10 iscommunicated with a bell-mouthed inlet 21 of the air blasting unit 20.

The inside air/outside air switching case 10 has a first inside airinlet 11 and a second inside air inlet 17 (described later in detail)through which the air in the vehicle compartment is introduced into theinside air/outside air switching case 10, and an outside air inlet 12through which the air outside the vehicle compartment is introduced intothe inside air/outside air switching case 10. The first inside air inlet11 and the second inside air inlet 17 open into the vehicle compartment,and the outside air inlet 12 opens into the engine room. The vehiclecompartment and the engine room are separated from each other by a dashpanel D.

A rotary door 13, which is an inside air/outside air switching door thatis used to switch the air that is introduced into the inside air/outsideair switching case 10 between the inside air and the outside air, isprovided at a position that is downstream of the first inside air inlet11 and the outside air inlet 12 in the direction of air flow. The rotarydoor 13 is arranged so as to pivot about right and left pivot shafts 13c. The rotary door 13 is formed of a peripheral wall 13 a having anarc-shaped cross section, and fan-shaped side plates 13 b that areformed at respective sides of the peripheral wall 13 a.

The peripheral wall 13 a pivots about the pivot shafts 13 c. Endportions of the pivot shafts 13 c protrude from the right and left sideplates 13 b, respectively, outward in the axial direction of the pivotshafts 13 c. The right and left pivot shafts 13 c are rotatablysupported by bearing holes 10 a formed in the inside air/outside airswitching case 10 (see FIG. 3). The pivot shafts 13 c are allowed torotate within a range of approximately 70 degrees.

Flanges 13 d are formed on the entire ends of the peripheral wall 13 aand flanges 13 e are formed on the entire ends of the side plates 13 b.The flanges 13 d are formed on the peripheral wall 13 a at the ends inthe circumferential direction of the peripheral wall 13 a, and projectfrom the ends outward in the radial direction. The flanges 13 e areformed at both ends of each of the right and left side plates 13 b, andproject from the ends outward in the axial direction of the pivot shafts13 c.

The rotary door 13 may be made of resin, for example, polypropylene, andis easily produced by forming the above-described portions 13 a to 13 eintegrally with each other. Thin gaskets 14 and 15 are fixed all overthe respective faces of the flanges 13 d and 13 e with, for example, anadhesive agent. The gaskets 14 and 15 provide airtight sealing when thefirst inside air inlet 11 or the outside air inlet 12 is closed by therotary door 13.

Thermoplastic elastomer is preferably used as the material for thegaskets 14 and 15. The thermoplastic elastomer is an elastic body thatexhibits rubber elasticity at ordinary temperatures and that softens andexhibits liquidity (thermoplasticity) at high temperatures. Therefore,the thermoplastic elastomer is formed into shapes in a manner similar toa manner in which ordinary thermoplastic resin is formed into shapes.Therefore, the gaskets 14 and 15 may be formed integrally with therotary door 13.

The first inside air inlet 11 has a peripheral portion opening 11 a thatfaces the peripheral wall 13 a of the rotary door 13 and side portionopenings 11 b that extend from the peripheral portion opening ha towardthe pivot shafts 13 c. That is, when the rotary door 13 opens the firstinside air inlet 11, not only a portion that corresponds to theperipheral wall 13 a of the rotary door 13 but also portions thatcorrespond to the side plates 13 b of the rotary door 13 are open. Incontrast, the outside air inlet 12 is formed only of a peripheralportion opening that faces the peripheral wall 13 a of the rotary door13.

The up-down direction, the right-left direction, and the front-reardirection shown in FIGS. 1 and 3 show the directions of the insideair/outside air switching device when the inside air/outside airswitching device is mounted in the vehicle. The pivot shafts 13 c forthe rotary door 13 are arranged at substantially the center of theinside air/outside air switching case 10 in the front-rear direction andbelow the inlets 11 and 12. Sealing faces 10 b and 10 c are formed atpositions posterior to the pivot shafts 13 c and sealing faces 10 d and10 e are formed at positions anterior to the pivot shafts 13 c. Thesealing faces 10 b, 10 c, 10 d and 10 e are inclined downward toward thepivot shafts 13 c. Sealing faces 10 f and 10 g are formed at positionsabove the pivot shafts 13 c.

The sealing faces 10 b to 10 g are formed in such a manner that flanges13 d and 13 e contact the sealing faces 10 d, 10 e, 10 f and 10 g whenthe rotary door 13 is at a position at which the inside air isintroduced into the inside air/outside air switching case 10 (positionindicated by two-dot chain lines in FIG. 1), and the flanges 13 d and 13e contact (are brought into surface contact with) the sealing faces 10b, 10 c, 10 f and 10 g when the rotary door 13 is at a position at whichthe outside air is introduced into the inside air/outside air switchingcase 10 (position indicated by solid lines in FIG. 1).

The inside air/outside air switching case 10 having the above-describedstructure includes at least two cases 10 j and 10 k that are separatelyformed. The inside air/outside air switching case 10 is formed byarranging the separate cases 10 j and 10 k next to each other in thelongitudinal direction of the rotary door 13, that is, the right-leftdirection of the vehicle and then connecting the cases 10 j and 10 kintegrally with each other. The sealing faces 10 b to 10 g are formedintegrally with the inside air/outside air switching case 10.

A switching link member 16 made of resin (see FIG. 3) is connectedintegrally with one end of the pivot shaft 13 c of the rotary door 13. Amanual operation force, which is applied to an inside air/outside airswitching operation member (e.g. manual operation lever) provided in anair-conditioning operation panel (not shown), is transmitted from theswitching link member 16 to the pivot shaft 13 c via, for example, acable to cause the rotary door 13 to pivot about the pivot shafts 13 c.

Alternatively, an actuator (e.g. motor) may be electrically actuatedwith the use of an inside air/outside air changeover switch in theair-conditioning operation panel, and the switching link member 16 maybe operated by the actuator so that the rotary door 13 pivots about thepivot shafts 13 c.

An air filter 30 is provided in the inside air/outside air switchingdevice. In the air filter 30, a filter member formed of, for example,corrugated Japanese paper or a porous urethane foam is supported by aframe made of resin. The air filter 30 has a flat plate shape as shownin FIG. 1, and removes dust in the air. When required, the filter membermay be provided with an absorbent, for example, activated charcoal,which absorbs malodorous components. In this way, the filter memberoffers deodorization performance.

In the inside air/outside air switching case 10, the air filter 30 isprovided at a position downstream of the pivot shafts 13 c of the rotarydoor 13 in the direction of air flow so that the air filter 30 does notinterfere with the pivot motion of the rotary door 13. The air blastingunit 20 includes a blast fan 22 formed of a centrifugal multibladeblower, a drive motor 23, and a casing 24. The casing 24 is made ofresin material, and formed in a scroll shape.

The blast fan 22 is driven by the motor 23 so that the air taken in theblast fan 22 through the inlet 21 flows outward in the radial directionof the blast fan 22 as indicated by an arrow A. An air outlet 25 of thecasing 24 is connected to an air-conditioning duct (not shown). Theblast fan 22 and the motor 23 may be included in an air blasting unitaccording to the invention.

A heat exchanger for cooling air, a heat exchanger for heating air, etc.are housed in the air-conditioning duct. The air delivered from the airblasting unit 20 is cooled, dehumidified, and re-heated while passingthrough the air-conditioning duct. In this way, the temperature of theair is adjusted. Then, the air is introduced into the vehiclecompartment.

The second inside air inlet 17 is formed in the inside air/outside airswitching case 10 at a side wall on the vehicle front side. In addition,the second inside air inlet 17 is formed at a position below the outsideair inlet 12. That is, the second inside air inlet 17 is formed at aposition between the rotary door 13 and the air filter 30. An inside airintroduction support door 18, which opens and closes the second insideair inlet 17, is arranged on the inner side of the second inside airinlet 17, that is, at a position closer to the rear of the vehicle thanthe second inside air inlet 17. The inside air introduction support door18 is arranged in such a manner that the inside air introduction supportdoor 18 does not interfere with the pivot motion of the rotary door 13.

As shown in FIGS. 1 and 4, the inside air introduction support door 18includes a door member 18 a, which is formed of a thin rectangularplate, and a pivot shaft 18 c. A gasket 18 b is fitted on a face of thedoor member 18 a, which faces the second inside air inlet 17. The gasket18 b provides airtight sealing when the inside air introduction supportdoor 18 a contacts a sealing face 17 a (see FIG. 1) in the side wall,which defines the second inside air inlet 17. Therefore, for example,porous elastic material, for example, a urethane foam or theabove-described thermoplastic elastomer may be used as the material forthe gasket 18 b.

Both ends of the pivot shaft 18 c are rotatably supported by bearingholes 10 h that are formed in the inside air/outside air switching case10, at positions above the second inside air inlet 17. When theoperation of the blast fan 22 does not operate, the inside airintroduction support door 18 according to the first embodiment of theinvention is oriented in the vertical direction (direction ofgravitational force) as indicated by solid lines in FIG. 1 so as toclose the second inside air inlet 17.

The inside air introduction support door 18 opens and closes the secondinside air inlet 17 in response to changes in the pressure in the insideair/outside air switching case 10. In the outside air mode in which theoutside air inlet 12 is opened and the first inside air inlet 11 isclosed by the rotary door 13, the pressure in the inside air/outside airswitching case 10 is determined based on the pressure of the outside airthat is introduced into the inside air/outside air switching case 10through the outside air inlet 12, that is, the pressure of the outsideair, which is influenced by the dynamic pressure that is generated whenthe vehicle travels, and the intake negative pressure that is generatedwhen the blast fan 22 is driven.

More specifically, when the blast fan 22 rotates at a high speed, theintake negative pressure increases and the pressure in the insideair/outside air switching case 10 decreases. When the vehicle travels ata high speed, the dynamic pressure increases and the pressure in theinside air/outside air switching case 10 increases. When the vehiclecompartment needs to be warmed up rapidly, for example, when a heater isturned on in winter, the voltage that is supplied to the drive motor 23is maximized to maximize the rotational speed of the blast fan 22 (tomaximize the volume of air delivered from the blast fan 22). In thisway, the maximum heating capacity is utilized. As a result, the pressurein the inside air/outside air switching case 10 falls below the pressurein the vehicle compartment.

That is, the intake negative pressure is introduced into the area nearthe inside air introduction support door 18, which causes a pressuredifference between the pressure in the area near the inside airintroduction support door 18 and the pressure in the vehiclecompartment, that is, the pressure outside the inside air/outside airswitching case 10. Namely, a pressure change is caused in the insideair/outside air switching case 10. With the use of this pressuredifference, the inside air introduction support door 18 pivots inwardfrom the inner wall face of the inside air/outside air switching case 10as indicated by two dot chains line in FIG. 1. As a result, the secondinside air inlet 17 is opened.

In other words, when the pressure in the inside air/outside airswitching case 10 is lower than the pressure of the inside air, theinside air introduction support door 18 moves away from the secondinside air inlet 17 and drawn inward from the inner wall face of theinside air/outside air switching case 10. As a result, the second insideair inlet 17 is opened. Thus, part of the inside air is drawn into theinside air/outside air switching case 10 through the second inside airinlet 17. The temperature of the inside air is higher than the lowtemperature of the outside air in winter. Therefore, if part of theinside air is mixed with the outside air, the temperature of the air atan inlet of the heat exchanger for heating air provided in theair-conditioning duct increases. As a result, the temperature of the airthat is warmed while the air passes through the heat exchanger forheating is made higher than that when only the outside air is introducedinto the inside air/outside air switching case 10. As a result, theheating efficiency is enhanced.

On the other hand, when the pressure in the inside air/outside airswitching case 10 is higher than the pressure of the inside air, theinside air introduction support door 18 is pushed against the inner wallface of the inside air/outside air switching case 10, more specifically,the inner wall face at a portion around the second inside air inlet 17.As a result, the second inside air inlet 17 is closed. Thus, it ispossible to avoid the situation where the low temperature outside airpasses through the second inside air inlet 17 and directly flows intothe vehicle compartment while the vehicle compartment is heated in theoutside air mode.

The opening amount of the inside air introduction support door 18, inother words, the volume of inside air that is introduced into the insideair/outside air switching case 10 through the second inside air inlet 17may be adjusted based on the relationship between the weight (gravity)of the inside air introduction support door 18 and the pressure of theair delivered from the blast fan 22. Accordingly, the required volume ofinside air that is introduced into the inside air/outside air switchingcase 10 may be ensured by changing the weight of the inside airintroduction support door 18.

A noise insulation member 19 is provided at a position that is outsidebut near the operation range of the inside air introduction support door18. The noise insulation member 19 blocks out the noise generated in theengine room, which proceeds from the outside air inlet 12 toward thesecond inside air inlet 17 when the outside air inlet 12 is open.

As shown in FIGS. 1, 2 and 4, the cross section of the noise insulationmember 19 is in a substantially L-shape. The noise insulation member 19is formed of a side portion 19 a and another side portion 19 b. Theinner side of the end portion of the side portion 19 a contacts theinside air introduction support door 18 at a portion near the top of thepivot shaft 18 c, that is, the upper end of the inside air introductionsupport door 18. A small space S1 is left between the lower end of theside portion 19 b and the upper face of the air filter 30 (see FIG. 1).

The space S1 left between the upper face of the air filter 30 and thenoise insulation member 19 is determined in such a manner that the airfilter 30 is attached to and detached from the inside air/outside airswitching case 10 without hindrance. In addition, a small space S1 isleft between each of both ends of the noise insulation member 19, thatis, the side portions 19 a and 19 b, and the inner wall of the insideair/outside air switching case 10 (see FIG. 4). That is, the noiseinsulation member 19 is formed so as to cover the inside airintroduction support door 18. The space S1 left between the inner wallof the inside air/outside air switching case 10 and the noise insulationmember 19 may be smaller than the space between the side portion 19 band the upper face of the air filter 30.

With this structure, the noise that is generated in the engine room andthat enters the inside air/outside air switching case 10 through theoutside air inlet 12 is blocked out by the noise insulation member 19.The noise generated in the engine room leaks toward the second insideair inlet 17 through the small spaces S1. However, the noise that leakstoward the second inside air inlet 17 is minimized because a labyrinthstructure is formed due to the small spaces S1.

Next, the operation of the inside air/outside air switching devicehaving the above-described structure will be described. The air that isintroduced into the inside air/outside air switching case 10 may beswitched between the inside air and the outside air by pivoting therotary door 13 about the pivot shafts 13 c. To select the outside airintroduction mode, the rotary door 13 is pivoted to the positionindicated by the solid lines in FIG. 1 (FIG. 3 shows the case where therotary door 13 is at the position at which the outside air is introducedinto the inside air/outside air switching case 10).

Thus, the peripheral wall 13 a of the rotary door 13 closes theperipheral portion opening 11 a of the first inside air inlet 11, andthe side plates 13 b of the rotary door 13 close the side portionopenings 11 b of the first inside air inlet 11. At the same time, theperipheral wall 13 a of the rotary door 13 moves away from the airflowpath on the outside air inlet 12 side. As a result, the outside airinlet 12 is fully open.

The gaskets 14 and 15 fixed to the flanges 13 d and 13 e of the rotarydoor 13 are pushed against (brought into surface contact with) thesealing faces 10 b, 10 c, 10 f and 10 g of the inside air/outside airswitching case 10. Therefore, surface-sealing is provided between theentire ends of the rotary door 13 and the inside air/outside airswitching case 10.

The space on the inner side of the rotary door 13 is entirelycommunicated with the outside air inlet 12 and a space upstream of theair filter 30 in the direction of air flow. Therefore, the outside air,which is introduced into the inside air/outside air switching case 10through the outside air inlet 12 when the blast fan 22 is driven, flowsthrough the space on the inner side of the rotary door 13 and uniformlyintroduced into the air filter 30.

Next, the introduced outside air passes through the air filter 30, andfine dust, malodorous components, etc. are absorbed in the air filter 30and therefore removed from the air. Then, the introduced outside airfrom which fine dust, malodorous components, etc. are removed is drawninto the air blasting unit 20 through the inlet 21 and delivered towardthe air-conditioning duct under pressure.

The intake negative pressure is introduced into the area near the airfilter 30 and the inside air introduction support door 18 when the blastfan 22 is driven, which causes a pressure difference between thepressure in this area and the pressure in the vehicle compartment, thatis, the pressure outside the inside air/outside air switching case 10.Due to this pressure difference, the inside air introduction supportdoor 18 opens the second inside air inlet 17. That is, the inside airintroduction support door 18 pivots to the position indicated by thetwo-dot chain lines in FIG. 1. As a result, the outside air isintroduced into the inside air/outside air switching case 10 through theoutside air inlet 12 and part of the inside air is introduced into theinside air/outside air switching case 10 through the second inside airinlet 17.

To select the inside air introduction mode, the rotary door 13 ispivoted clockwise by approximately 70 degrees from the positionindicated by the solid lines in FIG. 1 to the position indicated by thetwo-dot chain lines in FIG. 1. Thus, the gaskets 14 and 15 fixed to theflanges 13 d and 13 e of the rotary door 13 are pushed against (broughtinto surface contact with) the sealing faces 10 d, 10 e, 10 f and 10 gof the inside air/outside air switching case 10. Therefore,surface-sealing is provided between the entire ends of the rotary door13 and the inside air/outside air switching case 10.

As a result, the outside air inlet 12 is closed and the first inside airinlet 11 is fully open. The inside air, which is introduced into theinside air/outside air switching case 10 through the first inside airinlet 11 when the blast fan 22 is driven, flows through the space on theinner side of the rotary door 13 and is uniformly introduced into theair filter 30.

The introduced inside air passes through the air filter 30, and finedust, malodorous components, etc. are absorbed in the air filter 30 andtherefore removed from the air. Then, the introduced inside air fromwhich fine dust, malodorous components, etc. are removed is drawn intothe air blasting unit 20 through the inlet 21 and delivered toward theair-conditioning duct under pressure.

In the inside air introduction mode as well the intake negative pressureis introduced into the area near the air filter 30 and the inside airintroduction support door 18 when the blast fan 22 is driven, whichcauses a pressure difference between the pressure in the area and thepressure in the vehicle compartment, that is, the pressure outside theinside air/outside air switching case 10. Due to this pressuredifference, the inside air introduction support door 18 pivots to openthe second inside air inlet 17. As a result, the inside air isintroduced into the inside air/outside air switching case 10 through thefirst inside air inlet 11 and part of the inside air is introduced intothe inside air/outside air switching case, 10 through the second insideair inlet 17.

Next, the noise insulating effect provided by the noise insulationmember 19 will be described. FIG. 5 is a graph showing comparisonbetween the noise level when the noise insulation member is provided andthe noise level when no noise insulation member is provided. Morespecifically, FIG. 5 shows the comparison of the above-described noiselevels near the ear of an occupant in the front passenger seat in theoutside air introduction mode, in the case where the inside air/outsideair switching device is mounted in the vehicle. A solid line in FIG. 5shows the characteristic of the noise level when the noise insulationmember 19 is provided at a position that is outside but near theoperation range of the inside air introduction support door 18.

A dashed line in FIG. 5 shows the characteristic of the noise level whenno noise insulation member 19 is provided. The graph shows thatprovision of the noise insulation member 19 decreases the noise level inthe frequency range from approximately 1200 Hz to approximately 2500 Hz.

When the inside air/outside air switching device having theabove-described structure is in the outside air introduction mode, theoutside air is introduced into the inside air/outside air switching case10 through the outside air inlet 12 and part of the inside air isintroduced into the inside air/outside air switching case 10 through thesecond inside air inlet 17. Therefore, the noise generated in the engineroom enters the inside air/outside air switching case 10 through theoutside air inlet 12 and proceeds toward the second inside air inlet 17.However the noise generated in the engine room, which enters the insideair/outside air switching case 10 through the outside air inlet 12, isblocked out by the noise insulation member 19.

The noise generated in the engine room leaks toward the second insideair inlet 17 through the small spaces S1. However, the noise that leakstoward the second inside air inlet 17 is minimized because the labyrinthstructure is formed due to the small spaces S1. Thus, even if the secondinside air inlet 17 is open, the noise that leaks into the vehiclecompartment is minimized.

In addition, if the inside air introduction support door 18 is openedwith the use of the intake negative pressure that is generated when theblast fan 22 is driven, part of the inside air is introduced into theinside air/outside air switching case 10 through the second inside airinlet 17 not only in the outside air introduction mode but also in theinside air introduction mode. Also, a component used to open and closethe inside air introduction support door is, for example, a link member,is no longer necessary, which reduces the component cost.

Next, a second embodiment of the invention will be described. FIG. 6 isa perspective view showing the appearance of a noise insulation memberaccording to the second embodiment of the invention. As shown in FIG. 6,the noise insulation member 19 according to the second embodiment of theinvention is provided with side plates 19 c that are arranged atrespective longitudinal ends of the noise insulation member 19, and thatconnect the side portion 19 a and the side portion 19 b to each other.That is, the noise insulation member 19 is provided with side wallsformed of the side plates 19 c.

With this structure, the length of the space S1 between the upper faceof the air filter 30 and the noise insulation member 19 in the depthdirection and the length of the space S1 between the noise insulationmember 19 and the inner wall of the inside air/outside air switchingcase 10 in the depth direction are increased. Therefore, the noise thatis generated in the engine room that enters the inside air/outside airswitching case 10 through the outside air inlet 12 is reduced. Thus, itis possible to reduce the noise that leaks into the vehicle compartmentthrough the second inside air inlet 17.

Next, a third embodiment of the invention will be described. In theembodiments of the invention described above, the air filter 30 isprovided between the inside air introduction support door 18 and the airblasting unit 20. Instead of the air filter 30, an air volume adjustmentplate 40 may be provided. FIG. 7 is a view schematically showing theoverall structure of an inside air/outside air switching deviceaccording to the third embodiment of the invention. In the insideair/outside air switching case 10 according to the third embodiment ofthe invention, the air volume adjustment plate 40 is provided at aposition that is downstream of the inside air introduction support door18 in the direction of air flow, as shown in FIG. 7.

The air volume adjustment plate 40 is used as a substitute for the airfilter 30 after the air filter 30 is removed from the inside air/outsideair switching case 10. The air volume adjustment plate 40 is a pressureloss adjustment plate that is used to adjust the volume of the intakeair that is introduced through the inlets 11, 12 and 17. In the thirdembodiment of the invention, the air volume adjustment plate 40 has adraft resistance that is substantially equal to the draft resistance ofthe air filter 30. That is, the air volume adjustment plate 40 is formedin such a manner that the draft resistance thereof is substantiallyequal to the draft resistance of the air filter 30.

Therefore, the air volume adjustment plate 40 is formed in such a mannerthat the air volume adjustment plate 40 is easily attached to anddetached from the inside air/outside air switching case 10 as in thecase of the air filter 30, and is formed of a porous plate 41 that has alarge number of draft holes 42. Accordingly, if the air volumeadjustment plate 40 is arranged in place of the air filter 30 after theair filter 40 is removed, the volume of the air that passes through theair volume adjustment plate 40 is adjusted in a manner substantiallysame as that when the air filter 30 is arranged.

As in the embodiments of the invention described above, the noiseinsulation member 19 is arranged in such a manner that the inner side ofthe end portion of the side portion 19 a contacts the inside airintroduction support door 18 at a portion near the top of the pivotshaft 18 c, that is, the upper end of the inside air introductionsupport door 18. A small space S1 is left between the lower end of theside portion 19 b and the upper face of the air volume adjustment plate40 (see FIG. 7).

The amount of space S1 left between the upper face of the air volumeadjustment plate 40 and the noise insulation member 19 is determined insuch a manner that the air volume adjustment plate 40 is attached to anddetached from the inside air/outside air switching case 10 withouthindrance. Thus, the noise that is generated in the engine room thatenters the inside air/outside air switching case 10 through the outsideair inlet 12 is blocked out by the noise insulation member 19. A smallspace S1 is left between each of the both ends of the noise insulationmember 19, that is, the side portions 19 a and 19 b, and the inner wallof the inside air/outside air switching case 10 (see FIG. 4), as in theabove-described embodiments.

A fourth embodiment of the invention will be described. In theembodiments of the invention described above, the air filter 30 or theair volume adjustment plate 40 is arranged between the inside airintroduction support door 18 and the air blasting unit 20. However, theinside air/outside air switching case 10 that includes neither the airfilter 30 nor the air volume adjustment plate 40 may be used. FIG. 8 isa view schematically showing the overall structure of the insideair/outside air switching device according to the fourth embodiment ofthe invention.

As shown in FIG. 8, the air blasting unit 20 is provided at a positionthat is directly downstream of the inside air introduction support door18 in the direction of air flow. For example, the inside air/outside airswitching case 10 according to the fourth embodiment of the invention isused when the air filter 30 is provided in the air-conditioning duct(not shown) connected to a downstream-side portion of the air blastingunit 20.

Accordingly, a space S2 is left between the lower end of the sideportion 19 b of the noise insulation member 19 according to the fourthembodiment of the invention and an upper plate 24 a of the casing 24 ofthe air blasting unit 20. The space S2 is larger than the small spaceS1.

The space S2 according to the fourth embodiment of the invention is setin such a manner that the intake air introduced into the insideair/outside air switching case 10 through the second inside air inlet 17flows toward the inlet 21 of the casing 24. Therefore, when the secondinside air inlet 17 is opened in response of a change in the pressure inthe inside air/outside air switching case 10, the intake air introducedinto the inside air/outside air switching case 10 through the secondinside air inlet 11 is drawn by the blast fan 22.

With the inside air/outside air switching device having the structuredescribed above, the noise that is generated in the engine room thatenters the inside air/outside air switching case 10 through the outsideair inlet 12 is blocked out by the noise insulation member 19 that hasthe substantially L-shaped cross section. Accordingly, it is possible toreduce the noise that leaks into the vehicle compartment through thesecond inside air inlet 17.

In the embodiments of the invention described above, the noiseinsulation member 19 is larger than the inside air introduction supportdoor 18 when viewed in the front-rear direction of the vehicle.Alternatively, the noise insulation member 19 may be equal to or smallerthan the inside air introduction support door 18 when viewed in thefront-rear direction of the vehicle.

In the embodiments of the invention described above, the inside airintroduction support door 18 is formed by forming the door member 18 aand the pivot shaft 18 c integrally with each other and fitting thegasket 18 b to the door member 18 a. Alternatively, the inside airintroduction support door 18 may be formed by forming material, forexample, thermoplastic elastomer, in an elastically deformable sheetshaped plate door.

More specifically, a plate door is formed of a single sheet, and onlyone face of an upper portion of the sheet is fixed to an upper portionof the inner wall face around the second inside air inlet 17. Thus, thesecond inside air inlet 17 may be opened and closed in response to achange in the pressure in the inside air/outside air switching case 10.

In the embodiments of the invention described above, the inside airintroduction support door 18 may be opened and closed based on an intakenegative pressure generated by the blast fan 22. Alternatively, theinside air introduction support door 18 may be opened and closed by anactuator, for example, a servo motor.

While the invention has been described with reference to exampleembodiments thereof, it is to be understood that the invention is notlimited to the example embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exampleembodiments are shown in various combinations and configurations, whichare example, other combinations and configurations, including more, lessor only a single element, are also within the scope of the invention.

1. An inside air/outside air switching device, comprising: an insideair/outside air switching case that has an outside air inlet which opensinto an engine room, a first inside air inlet which opens into a vehiclecompartment, and a second inside air inlet which opens into the vehiclecompartment and which is formed in a side wall of the inside air/outsideair switching case; an inside air/outside air switching door that isprovided in the inside air/outside air switching case, and that switchesan open inlet between the first inside air inlet and the outside airinlet; an inside air introduction support door that opens and closes thesecond inside air inlet; and a noise insulation member that is providedin such a manner that the noise insulation member does not interferewith an operation of the inside air introduction support door, and thatblocks out noise which is generated in the engine room and whichproceeds from the outside air inlet toward the second inside air inletwhen the outside air inlet is open.
 2. The inside air/outside airswitching device according to claim 1, further comprising an airblasting unit that is provided at a position which is downstream of theinside air introduction support door in a direction of air flow, andthat takes in air introduced into the inside air/outside air switchingcase through the inlets, wherein: the inside air introduction supportdoor is provided at a position that is downstream of the insideair/outside air switching door in the direction of air flow and that ison an inner side of the second inside air inlet, moves inward from aninner wall face of the inside air/outside air switching case when theinside air introduction support door opens the second inside air inlet,and opens and closes the second inside air inlet based on a change in apressure in the inside air/outside air switching case when the outsideair inlet is open; and the noise insulation member is provided at aposition outside but near an operation range of the inside airintroduction support door.
 3. The inside air/outside air switchingdevice according to claim 2, wherein: the pressure in the insideair/outside air switching case when the outside air inlet is open isdetermined based on a pressure of outside air that is introduced intothe inside air/outside air switching case through the outside air inletand an intake negative pressure that is generated when the air blastingunit is driven; when the pressure in the inside air/outside airswitching case is lower than a pressure of inside air, the inside airintroduction support door is drawn inward from the inner wall face toopen the second inside air inlet; and when the pressure in the insideair/outside air switching case is higher than the pressure of the insideair, the inside air introduction support door is pushed against theinner wall face of the inside air/outside air switching case to closethe second inside air inlet.
 4. The inside air/outside air switchingdevice according to claim 2, wherein: the noise insulation member isprovided in such a manner that the noise insulation member covers theinside air introduction support door; a space, through which the airthat is introduced into the inside air/outside air switching casethrough the second inside air inlet flows, is left between adownstream-side end of the noise insulation member and an upper plate ofthe air blasting unit; and an end of the noise insulation member, whichis on an opposite side of the downstream-side end, contacts the innerwall face of the inside air/outside air switching case.
 5. The insideair/outside air switching device according to claim 4, wherein: thenoise insulation member is formed of two side portions, and has asubstantially L-shaped cross section; and an inside face of an end ofone of the side portions, which is the end on the opposite side of thedownstream-side end of the noise insulation member, contacts an upperend of the inside air introduction support door.
 6. The insideair/outside air switching device according to claim 5, wherein: sideplates are provided at respective longitudinal ends of the noiseinsulation member; and each of the side plates connects one of the sideportions to the other side portion.
 7. The inside air/outside airswitching device according to claim 2, further comprising an air filterthat is provided between the inside air introduction support door andthe air blasting unit, and that filters the air introduced into theinside air/outside air switching case through the inlets, wherein: thenoise insulation member is provided in such a manner that the noiseinsulation member covers the inside air introduction support door; asmall space is left between a downstream-side end of the noiseinsulation member and the air filter; an end of the noise insulationmember, which is on an opposite side of the downstream-side end,contacts the inner wall face of the inside air/outside air switchingcase; and a small space is left between each of both longitudinal endsof the noise insulation member and the inner wall face of the insideair/outside air switching case.
 8. The inside air/outside air switchingdevice according to claim 7, wherein: the noise insulation member isformed of two side portions, and has a substantially L-shaped crosssection; and an inside face of an end of one of the side portions, whichis the end on the opposite side of the downstream-side end of the noiseinsulation member, contacts an upper end of the inside air introductionsupport door.
 9. The inside air/outside air switching device accordingto claim 8, wherein: side plates are formed at respective longitudinalends of the noise insulation member; and each of the side platesconnects one of the side portions to the other side portion.
 10. Theinside air/outside air switching device according to claim 2, furthercomprising an air volume adjustment plate that is provided at a positionwhich is downstream of the inside air introduction support door in thedirection of air flow, and that has a draft resistance which issubstantially equal to a draft resistance of an air filter that filtersthe air introduced into the inside air/outside air switching casethrough the inlets, wherein: the noise insulation member is provided insuch a manner that the noise insulation member covers the inside airintroduction support door; a small space is left between adownstream-side end of the noise insulation member and the air volumeadjustment plate; an end of the noise insulation member, which is on anopposite side of the downstream-side end, contacts the inner wall faceof the inside air/outside air switching case; and a small space is leftbetween each of both longitudinal ends of the noise insulation memberand the inner wall face of the inside air/outside air switching case.11. The inside air/outside air switching device according to claim 10,wherein: the noise insulation member is formed of two side portions, andhas a substantially L-shaped cross section; and an inside face of an endof one of the side portions, which is the end on the opposite side ofthe downstream-side end of the noise insulation member, contacts anupper end of the inside air introduction support door.
 12. Theinside-air/outside air switching device according to claim 11, wherein:side plates are formed at respective longitudinal ends of the noiseinsulation member; and each of the side plates connects one of the sideportions to the other side portion.
 13. The inside air/outside airswitching device according to claim 1, further comprising: a servo motorthat opens and closes the inside air introduction support door.